Acoustical panels



Jan. 21, 1969 GREASON ET AL 3,422,920

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United States Patent 3,422,920 ACOUSTICAL PANELS David M. Greason, Newark, and Hale J. Sabine, Granville, Ohio, assignors to Owens-Corning Fiberglas Corporation, a corporation of Delaware Filed July 1, 1965, Ser. No. 468,867

US. Cl. 181-33 Int. Cl. E04b 1/82 Claims ABSTRACT OF THE DISCLOSURE This invention relates to acoustical panels of bonded fibers for installation as wall, ceiling or other surfacing structures. More particularly the invention pertains to such panels or boards having effective theremo-insulating properties as well as effective sound absorption.

Panels of this invention are preferably composed of bonded, compressed masses of glass fiber. Such porous, low-density bodies of fibrous glass are most effective in noise abatement due to the capacity of the myriad, minute communicating air cells in the maze of fibers to bafile and absorb sound waves. The tiny pockets of static air are also responsible for the high thermal insulating power of such fibrous masses. Such panels, mats, sheets, boards or tiles formed of compressed mineral fibers as, for example, glass fibers have been found to be admirably suited as acoustic attenuating, wall or ceiling surfacing materials, but it is to be understood that wall boards or surfacing sheets formed of other fibrous material such as vegetable fibers or animal fibers may be utilized in forming the boards, panels, sheets or tiles of this invention.

These fibrous glass panels are conventionally supplied in various planar dimensions ranging from ten by ten inches for acoustical tile up to and beyond four feet by eight feet for wall tile board. The more common thicknesses are one-half and three-fourths of an inch, but the broader boards are occasionally used in thicknesses up to two inches.

These products, when employed in ceiling installations, are generally attached by adhesives or hung upon mechanical suspension systems. The large panels are also laid upon framework as form boards in roof construction where they carry 'poured-in-place gypsum decks generally two inches in depth.

From the standpoint of lightness and acoustical effectiveness of the boards, glass fibers of a diameter in the area of fifty hundred-thousandths of an inch serve most satisfactorily. Fibers of still smaller diameters would enhance some properties of the products, while fibers of larger dimensions up to more than seventy hundred-thousandths, give adequate results and may be practical for some commercial purposes.

The size of the fibers is determined by the type and control of the forming equipment utilized. Such apparatus ordinarily employs air, steam, or combusition gases for attenuating molten threads of glass issuing from small orifices. However created, the fibers are collected at the forming station in blanket form with an uncured binder component dispersed therethrough.

A binder composed of a combination of melamine and phenol formaldehyde resins in a proportion of roughly one to two, has acceptable strength and fire resistant characteristics. Various other fibrous glass bonding agents are well-known and would be equally effective. These include epoxy, urea, and polyster resins. The amount of binder may run between seven and fifteen per cent by weight of the finished panel, depending upon the balance desired between sturdiness and fire protection.

The blanket of fibers with the uncured binder dispersed therethrough is held compressed to the desired density in the final board while the binder is set by heat. The compressed mass is thus dimensionally stabilized. The density generally runs between eight and twenty five pounds per cubic foot. The individual panels or boards are created by a longitudinally slicing and cross-Wire shearing the compressed fibrous blanket according to the selected measurements.

In order to admit sound, the surfaces of the resulting boards must be either of a porous nature or must be composed of a thin, unattached film with sufiicient flexibility to vibrate and thus transmit sound waves to the interior of the panel. This plastic covering may be variously colored or be imprinted with a decorative pattern. The smooth film is generally preferred over the other type of porous openings because it is more easily washed and discourages dust accumulation. In contrast, the porous paint surfaces are sometimes inclined to disintegrate upon washing and to smudge easily.

To prevent or minimize transmission of sound waves from the room where the sound originates through the acounstical panels a number of means have been developed for backing the panels. For example, US. Patent No. 3,122,216 discloses a panel of mineral fibers which has on its rear face an integrated impervious membrane, while US. Patent No. 3,111,188 discloses a panel of mineral fibers which has on its rear face an integrated and impervious coating of paint. Both of these coatings are designed to prevent transmission of sound straight through the back or rear surface of the panel. The first mentioned patent also discloses a means for partially sealing the edge of the panels to prevent sound leakage through or out of the edge. However, attempts to date to edge-seal panels have been expensive and difficult to produce in mass fashion.

It is, then, an object of this invention to provide an improved acoustical panel having means for reducing the leakage of sound waves from the edges of the panel.

It is a further object of this invention to provide an improved acoustical panel having a novel means to reduce sound transmission therethrough without disturbing the appearance or esthetic appeal of the panel on the exposed or front surface side.

It is a still further object of this invention to provide a sturdy panel of bonded mineral fibers, preferably of fibrous glass, having high acoustical properties and which may be produced more economically than prior products achieving the same effect.

A further object of this invention is to provide acoustical tiles or boards of improved appearance.

The invention features an acoustical panel comprising a substantially rigid body of bonded fibers, preferably mineral fibers, having a sound blocking coating on a rear planar surface thereof and a sound blocking coating around the perimeter of a front planar surface defining a sound admitting area cenerally located within the perimeter.

More specifically, the invention features an acoustical panel having a main, generally rigid and self-sustaining, porous body of fibers integrated by a binder. A nonvibratile coating may be continuously and rigidly attached to the rear planar side of the main body of fibers to prevent sound transmission therethrough. A front sealing coat having sound blocking properties may be applied around the perimeter of a face of the panel defining a centrally located sound admitting surface. Sound thus admitted to the panel through this surface is trapped in and attenuated between the rear coating and the perimetrical front coating, and is eventually absorbed, to prevent leakage of sound through the edge of the tile.

If a different or more decorative appearance is required or desired, a self-supporting film may be applied in intimate contiguous unbonded contact with the face of the panel over the sound admitting surface and extending over the perimetrical coating to continue the design appearance. The film is responsive to transmit sound energy within the panel for attenuating sound waves. Any one of a number of suitable means may be utilized for securing the film in place. Alternatively, to improve or change the appearance, a decorative coating of sound porous paint may be applied over the face of the panel over both the perimetrical coating and the sound admitting surfaces.

A second embodiment of the invention features an acoustical panel having a substantially rigid porous body with a sound blocking coating applied to the rear planar surface of the body and a sound blocking coating applied to the front surface of the body. The front coating may have sound admitting apertures formed therein in a central area surrounded by a perimetrical area which is still substantially impervious to sound. The front coating may have a two dimensional exposed surface finished to represent a three dimensional surface having shadowed and high-lighted areas with the apertures being formed in the shadowed areas of the sound admitting area of the front coating to maintain substantially the same appearance as the three dimensional appearance of the perimetrical area that does not have apertures. The above front coating may be a film carrying a photographic or printed representation of a desired three dimensional surface having shadowed and high-lighted areas.

In carrying the design appearance further the front coating may have an exposed face with three dimensional embossments formed thereon either with or without photographic or printed three dimensional representation in addition thereto, to provide high-lighted and shadowed areas. Again the apertures are formed in the shadowed or the depths of the embossed areas of the sound admitting area to maintain substantially the same appearance as the perimetrical area which has no sound admitting apertures.

An additional embodiment described herein includes a front coating having a covering on the exposed face with dark and lighter areas, for example, the salt and pepper appearance that is popular with some designers. The apertures are then formed to coincide with the dark areas of the sound admitting area to maintain substantially the same appearance as the dark areas of the perimetrical area which has the repeated pattern shown thereon but does not have apertures formed therein.

Further objects, advantages and features of this invention will become apparent when the following description is taken in conjunction with the accompanying drawings, in which:

FIGURE 1 is a side elevation, with a portion shown in vertical section, of an acoustical panel representing a prior art approach;

FIGURE 2 is a side elevation, with a portion shown in veltical section, of an acoustical panel embodying this invention;

FIGURE 3 is a front elevation of the panel of FIGURE 2 more clearly illustrating the perimetrical coating of this invention;

FIGURE 4 is a side elevation in vertical section illustrating sound paths through different panels;

FIGURE 5 is a side elevation in vertical section illustrating a second embodiment of the teachings of this invention;

FIGURE 6 is a front elevation of an acoustical panel illustrating a third embodiment of the teachings of this invention;

FIGURE 7 is an enlarged side view in vertical section of a fourth embodiment of the teachings of this invention; and

FIGURE 8 is a front elevational view of a section of acoustical panel illustrating a fifth embodiment of the teachings of this invention.

Referring to FIGURE 1, there is illustrated an acoustical panel noting one of the attempts of the prior art to solve the problem of sound leakage through an edge. The panel has a main body portion 12 composed preferably of bonded glass fibers. Upon the upper or back surface, and also upon the side edges of the panel, is a membrane 14 which may be an aluminum foil which is firmly attached to the main body 12 by an adhesive 15. The membrane tightly seals the rear face and the edges of the panel. The membrane 14 should be non-vibratile, of a flexible nature for purposes of securing and thoroughly adhered to the panel. The membrane or coating may be composed of a metal film such as the aluminum foil adhesively attached to the body of the panel. An aluminum foil with a thickness of in the range of seven ten-thousandths to two thousandths of an inch serves very satisfactorily. The adhesive providing such attachment may be separately applied or may be a thermoplastic film such as polyethylene previously joined through tissue to the metal foil. This laminate may be attached to the panel by hot pressing.

Alternately, the membrane or coating may be a synthetic plastic sheet of film, either self adhered through heat treatment or adhered with an intermediate adhesive. Plastic films which have the desired qualities of elasticity and strength include the non-rigid, vinyl chloride polymers and co-polymers, vinyl chloride polymer-nitrile rubber blend, and polyethylene. Such films may be two-thousandths of an inch in thickness. An adhesive which functions well on this surface is an elastomer cement type having a synthetic rubber base in a somewhat higher proportion of a ketone solvent. It has high strength and excellent adhesion and is resistant to vinyl plasticizers, oil or other aliphatic hydrocarbons. Various other thermoplastic, thermo-setting and elastomeric adhesives would perform quite effectively and are available in liquid form permitting their application by spray or roller.

The above two examples of the metal film and plastic sheet of film are intended to be representative of a number of substantially sound impervious coatings which have been applied to the back planar surface of acoustical tiles or panels in the past to prevent sound transmission therethrough. As shown in FIGURE 1 attempts have been made to utilize a sound shielding extension 16 on the side edges of the panel to prevent sound leakage from the edges of the acoustical panel.

The manner in which this leakage occurs is illustrated in FIGURE 4. Referring to the right-hand tile, sound waves represented by the arrows enter a sound admitting surface 18 of the tile, leak out from the edges of the tile and past a suspension system 13 or other means utilized to hold the panels in place. The sound that is leaked through the edges then is freed to proceed to adjacent areas where it is not desired.

Referring to FIGURES 2 and 3, there is illustrated an embodiment of the teachings of this invention in which it has been found that a backing or coating 14 which may be adhered by an adhesive 15 need only be applied to the rear planar surface of the body 12 of the tile. In order to prevent sound transmission through the edges of the tiles, a perimetrical coating 17 of a sound blocking or sound impervious character is applied to the tile or panel.

As illustrated in FIGURE 4, the panel to the left having the perimetrical coating 17 allows the sound to enter the panel through a centrally located sound admitting area 18 and the sound, represented by the arrows, is attenuated between the rear coating 14 and the perimetrical coating 17 and is substantially, if not entirely, absorbed and prevented from leaking through the edges of the tile and proceeding to other areas. The coating 17 may be any of the previously described sound impervious coatings or it may constitute a clear vinyl overspray if one desires to substantially maintain the appearance of the tile or panel by putting a transparent coating 17 around the perimeter. In any event the coating 17 is to be of a substantially sound impervious or sound blocking nature. Sounds from the room are admitted to the centrally located area 18 of the tile or panel and are absorbed within the panel thus reducing sound within the room as well as attenuating its progress to areas outside the room in which the panel is installed.

Another sealing or sound blocking coating is described in Patent No. 3,111,188 and comprises a paint coating which may be a water emulsion, pigmented with a clay filler and with just sufiicient binder, such as poly vinyl acetate, to hold the pigment particles together and to close the pores.

Although the symmetrical configuration illustrated in the face view of FIGURE 3 is appealing in appearance and may suflice for a great many applications, it is desirable to be able to change the design appearance of the tile without affecting its acoustical qualities. Referring to FIGURE 5, there is shown the main body 12 of bonded fibers having a backing 14 adhesively applied at 15 as described hereinbefore, and a perimetrical sound blocking coating 17 on the front face of the tile or panel. To provide a uniform appearance across the face of the tile a coat of porous covering material such as paint, which will disguise the perimetrical sound blockng area 17 while admitting sound waves to the sound admitting area 18, may be applied over both the perimetrical and sound admitting areas. Such paints are well known in the prior art and will not be described in detail here.

Alternatively, a self-supporting film of yieldable or flexible material, preferably a resinous or plastic material, may be applied as the coating 20 over the perimetrical and sound admitting areas on the face of the panel. Such a film is described in US. Patent No. 3,151,700.

The resin or plastic film covering is applied by pressure so as to lie unattached but in intimate contiguous contact with the uncoated regions 18 of the face of the tile. An adhesive or bonding agent 19 may be utilized between the film 20 and the perimetrical coating 17. Through the adhesive or securing juncture of the film at the edge regions of the body coupled with a substantial pressure forcing the film into intimate contiguous contact with all areas adjacent the major surface of the body, the film may be mechanically integrated or held in fixed relation to the body and the surface contour engaged by the film. As the pliable film is comparatively thin, it may be readily vibrated under the influence of sound waves and hence the acoustical properties of the porous body 12 are not appreciably modified by the film facing or covering. The resin film is preferably of a thickness of about 2 mils. This thickness has been found to function satisfactorily, having effective vibratile characteristics to enhance sound-attenuation and minimizes the amount of resin used for the facing.

However, good results have been obtained through the use of films of between one mil and eight mils in thickness. The use of a thicker film tends to reduce the acoustic properties or sound-attenuating characteristics to a certain extent. The thin film effects more eflicient soundattenuation. In the interests of economy and for eflicient sound-attenuation it is preferable to make the film as thin as is practical commercially.

Various kinds of resinous or plastic self-supporting films may be employed as the secondary or finish coating 20 or covering on the tile. Self-supporting films of the following materials may be also employed, monopolymer chloride, polyethylene, polyvinyl fluoride, polycarbonate, and polyester films such as marketed under the trade name Mylar. The acoustic properties of the product in a measure reside in the ability of a film-facing to vibrate in order to transmit sound into the panel to effectively dissipate or attenuate sound energy.

A still further embodiment of the teachings of this invention is illustrated in FIGURE 6, which shows a face view of an acoustical tile or panel. In this instance the perimetrical sound blocking area 17 has been covered by a film or other coating having a two dimensional surface with a photographic or printed representation of a three dimensional surface printed thereon. Such coatings 30 are available commercially, for example, as plastic films which have wood grain printings thereon with randomly spaced grooves 31 and the graining 32 both represented by shadowed and high-lighted areas that are printed into or on the two dimensional surface. Similar coatings 30 may be printed or photographically represented and directly applied to a surface or face of the tile 20 over the perimetrical area 17 without utilizing a separate film. Since most of these commercially available coatings are in themselves sound impervious, apertures such as the pin holes shown at 33 must be utilized in order to admit the sound waves to the acoustical body. It will be noted that the pin holes are formed in the dark or shadowed areas of the design coating so that their appearance is not readily detectable. In the specific instance shown in FIG- URE 6, the apertures or perforations 33 may be formed in the dark or shadowed grain areas 32. Although a wood grain finish has been illustrated in FIGURE 6, other three dimensional appearances may be provided as desired by the two dimensional printing or photographic or other representation.

Referring now to FIGURE 7, there is illustrated a still further embodiment of this invention in which a coating 40 is applied to the front face of the acoustical body 12. As shown in the cross sectional view of FIGURE 7, the coating 40 may be of the sound blocking type throughout its entire surface. The coating 40 is advantageously a plastic film having a surface with embossments 41 formed therein which, along With printing or photognaphic representations that may be made in the surface of the coating 40, may represent a desired three dimensional surface. Again such a surface for purposes of illustration here, might be a wood grain surface. Since the coating 40 is substantially impervious to sound, apertures 43 must be formed therethrough into the body 12 of the acoustical panel to admit sound waves. As will be noted in FIGURE 7, no apertures, perforations, slits, etc. are formed in the perimetrical area to provide the effects taught hereinbefore. However, the apertures 43 may be formed in the sound admitting area 18 at the depths of the embossments 41 so that the apertures are essentially invisible to all but a most detailed inspection of the surface of the panel. It will be noted that a preliminary perimetrical coating 17 has been omitted in this embodiment since the perimeter area of the coating 40 may accomplish the same result. If "the film 30 in FIGURE 6 is of a sound bvlocking material, the preliminary coating 17 may similarly be omitted in that embodiment.

Referring to FIGURE 8 there is illustrated a still further embodiment of the teachings of this invention in which a portion of a front face of 'a tile or acoustical panel is shown having a perimetrical coating 17 to provide the desirable sound attenuating results discussed herenrbetore. Ove-nlaying the perimetrical coating 17 and the sound admitting area 18 'may be a coating having geometrically disposed or randomly disposed darker and lighter areas. This may be similar tothe salt and pepper effect popular in some designs. It will be noted however that in forming the apertures to admit sound to the area 18 that holes 50 are formed of substantially the same diameter as the dark or shaded portions of the pattern 51 on the perimetrical area so that under most lighting conditions the apertures 50 and a dark dot or spot 51 appear to be of the same significance inthe design. Thus, sound is admitted to the area 18 only through the apertures or holes 50, while the holes 50 and the dark spots or dots 51 combine to present a substantially uniform appearance on the face of the tile.

The invention includes the use of film discussed hereinbefore wherein the film is bonded only to the perimetrical area of the front face to provide a sound blocking coating. The area of film within the perimetrically bonded area is left free to vibrate to transmit sound energy to the interior of the panel for attenuation.

It is to be noted that the dimensions shown in the drawings are without significance since in most cases the dimensions have been enlarged to clearly show the invention. It will be realized that proper dimensioning in actual practice would reveal very thin coatings and substantially invisible perforations in those instances where applicable. It is also apparent that, within the scope of the invention, modifications and diiferent arrangements may be made other than herein disclosed, and the present disclosure is illustrative merely, the invention comprehending all variations thereof.

We claim:

1. An acoustical panel having a main, generally rigid and self-sustaining, porous body of fibers integrated by a binder, a non-vibratile coating continuously attached to the rear planar side of the main body of fibers, and a front sealing coat of sound blocking properties applied around the perimeter of a face of said panel defining a centrally llocated sound admitting surface, sound admitted to said panel through said surface being trapped and at tenuated between said rear coating and said perimetrical front coating to prevent leakage of sound waves through the edge of the tile.

2. An acoustical panel as defined in claim 1 in which a decorative, self-supporting film is applied in intimate contiguous unbonded contact with the face of said panel over said sound admitting surface and extending over said perimetrical coating to continue design appearance, said film being responsive to sound energy for attenuating sound waves, and means for securing said film in place.

3. A11 acoustical panel as defined in claim 1 in which a decorative coating of sound porous paint is applied on the face of said panel over said perimetrical coating and said sound admitting surface.

4. An acoustical panel having a substantially rigid porous body, a sound blocking coating applied to the rear planar surface of said body, and a sound blocking coating applied to a front surface of said body, said front coating having sound admitting apertures formed therein in a central area surrounded by a perimetrical area still substantially impervious to sound, sound admitted to said panel being attenuated between said rear coating and said perimetrical area of said front coating to substantial'ly prevent leakage of sound through the edges of said panel.

5. A panel as defined in claim 4 in which said front coating has a two dimensional exposed surface finished 6 to represent a three dimensional surface having shadowed and highlighted areas, said apertures being formed in said shadowed areas of the sound admitting area of the front coating to maintain substantially the same appearance as the three dimensional appearance of said perimetrical area without apertures.

6. A panel as defined in claim 5 in which said front coating is a film carrying a photographic representation of a desired three dimensional surface having shadowed and high-lighted areas.

7. A panel as defined in claim 4 in which said front coating has an exposed face with three dimensional embossments formed thereon to provide high-lighted and shadowed areas, said apertures being formed in shadowed areas of said sound admitting area to maintain substantially the same appearance as said perimetrical area.

8. A panel as defined in claim 4 in which said front coating includes a covering on the exposed face 'h-aving dark and lighter areas, said apertures being formed in the dark areas of said sound admitting area to maintain substantially the same appearance as said perimetrical area.

9. An acoustical panel comprising a substantially rigid body of sound insulation material having a sound blocking coating on a rear planar surface and a sound blocking coating around the perimeter of a front planar surface defining a central sound admitting area and 'uncoated edges, said rear sound blocking surface cooperating with said perimetrical sound blocking front surface to attenuate sound admitted through said central area and prevent sound leakage through uncoated edges of the panel.

10. An acoustical panel comprising a substantially rigid body of bonded mineral fibers having a sound blocking coating on a rear planar surface and a film covering a front planar surface, said film being bonded to a perimetrical area of said front surface to provide a sound blocking coating, said film being substantially free to -vibrate within said perimetrical area to transmit sound energy to the interior of said panel.

References Cited UNITED STATES PATENTS 1,959,057 5/1934 Kliefoth 181--33 2,253,953 8/1941 Dunbar 18133 2,967,583 1/1961 Jack 18133 3,087,577 4/1963 Prestia 18133 3,111,188 11/1963 Rees et al 181-33 3,122,216 2/1964 BoltZ et al. 18133 3,151,700 10/1964 Feid 18133 3,183,996 5/1965 Capaul 181-33 3,186,895 6/1965 MacDonald 181-33 3,234,996 2/1966 King et al 181-33 3,246,063 4/1966 Podgurski 181-33 FOREIGN PATENTS 247,862 2/ 1961 Australia.

252,347 6/ 1964 Australia.

604,078 8/1960 Canada. 1,050,975 9/ 1953 France.

851,315 10/1960 Great Britain.

906,463 9/1960 Great Britain.

963,632 7/1964 Great Britain.

ROBERT S. WARD, JR., Primary Examiner.

U.S. Cl. X.R. 161-44 

